Hepatocyte growth factor (HGF) is a powerful mitogen which stimulates the hepatocyte proliferation. The single receptor for HGF, c-Met, is a transmembrane protein encoded by proto-oncogene c-Met. HGF activates c-Met, which results in the cascade activation by the signal transduction pathway, such as ras/mitogen-activated protein (MAP) kinase pathway, and phosphatidylinositol 3-kinase/protein kinase B pathway. A series of biological effects, such as scattering, cell movement, invasion, cell migration and eventual metastasis, occur in cells.
The human HGF gene is located on the long arm of chromosome 7 (7q21.1), has about 70 kb, and comprises 18 extrons and 17 introns. HGF is produced mainly from interstitial cells. The mature HGF has a molecular weight of 9.0×104. An alpha chain of 6.0×104 and a beta chain of 3.0×104 are connected by a disulfide linkage to form a heterodimer. The alpha chain is in a short hairpin structure and has an N-terminal region in which 4 Kringle domains are connected. The hairpin structure in the N-terminal region and the structure of its first two Kringle domains are essential for HGF to perform its biological effect. The beta chain has a serine protease-like structure, but has no catalytic activity of the protease. However, the beta chain is a prerequisite for HGF to perform its biological activity.
The human c-Met gene is located on the long arm of chromosome 7 (7q31), has about 110 kb, and comprises 21 extrons. In a mature c-Met, an alpha subunit of 5.0×104 and a beta subunit of 1.4×105 form a heterodimer. The alpha subunit is located on the exocellular part. The beta subunit includes the exocellular region, the transmembrane region and the intracellular region. The alpha subunit and the exocellular region of the beta subunit serve as the ligand recognition site and incorporate HGF. The intracellular region has a tyrosine kinase activity, and is a site where several signaling molecules, interact.
The HGF/c-Met signal transducting path is widely present in a variety of cells, and has a significant physiological adjustment effect on the growth and development of tissues and organs. However, the over-expression of HGF or c-Met in cells generally results in the invasion and metabasis of tumor cells.
The HGF/c-Met signal system is closely relevant to the invasion and metabasis of tumor cells. When stably transfecting cDNA of HGF to low metastatic cell line SMMC and comparing the cell growth and the cell mobility before and after the transfection, the results show that the high expression of HGF in the hepatoma carcinoma cells can promote the growth, invasion and metabasis of hepatoma carcinoma cells. It is found by Miura, et al. that the invasion of hepatoma carcinoma cell line AH109A is mediated by the paracrine secretion and autocrine of HGF. In the poorly differentiated tumors and the recurrent patients having the early primary hepatocellular carcinoma, c-Met is in an over-expression.
The down-regulation or the abnormal regulation of Met and/or HGF, the over-expression of Met and the mutation of Met are all relevant to the uncontrolled cell proliferation and survival. These factors occur in the early stage of tumors and play a key role in the invasion, growth and metabasis of tumor cells. The over-expression of Met and HGF are relevant to poor prognosis and diagnosis. Up to now, much evidence demonstrates that HGF is acting as a regulator in the cancer occurrence, invasion and metabasis. In the mouse model of tumor xenograft, inhibition of Met results in the tumor growth slowdown, which is because the specific antibody of c-Met has been expressed to block the combination of HGF and c-Met. Moreover, c-Met is also over-expressed in the cells of nonsmall-cell lung cancer and small-cell lung cancer, lung cancer, breast cancer, colon cancer and prostatic carcinoma. Since c-Met appears to play an important role in tumor formation of several tumors, several inhibition strategies have been applied to therapeutically target the receptor tyrosine kinase, which also makes Met the important target in the development of anticancer drugs.
Modulation of the HGF/c-met signaling pathway may be effected by regulating binding of HGF beta chain to c-Met. In particular embodiments, the zymogen-like form of HGF beta mutant was shown to bind c-Met with 14-fold lower affinity than the wild-type serine protease-like form, suggesting that optimal interactions result from conformational changes upon cleavage of the single-chain form (US 2005/0037431). Extensive mutagenesis of the HGF beta region corresponding to the active site and activation domain of serine proteases showed that 17 of the 38 purified two-chain HGF mutants resulted in impaired cell migration or c-Met phosphorylation, without loss in Met binding. However, the reduced biological activities were well correlated with reduced Met binding of corresponding mutants of HGF beta itself in assays eliminating dominant alpha-chain binding contributions (CN200780029441.2).
Based on the relevant prior art references, the present inventors design and synthesize a series of quinoline deravatives comprising 1,2,4-triazine-3,5-dione. By an in-vitro activity screen, it is shown that this series of compounds have an anti-tumor activity.